Ashfall by Mike Mullin

A super volcano erupts in Yellowstone Park sending a meteor into 16-year-old Alex's house in Cedar Falls, Iowa. He's home alone, and after extricating himself from his fire-engulfed room he heads to the neighbors who take him in as sonic booms echo for days and ash falls down like snow. Alex is determined to find his family so he sets off on his dad's cross-country skis. His trek takes him through an inhospitable landscape with gritty ash falling constantly. Along the way he sees humanity change as much as the environment, with most people out for their own survival. Mullen weaves a gripping and powerful adventure story of surviving a cataclysmic event while also unfolding Alex's journey from self-absorbed teen to thoughtful, caring adult.